To my right, a tanned man with bulging biceps watches wisps of cloud shroud mountains in the near distance.

Directly in front, children yell inconceivable words into their snorkels, excited by the amazing creatures they've seen below the water.

On my left, two elderly women in floral one-piece bathers sit at the shore with their legs being kissed by gentle waves.

Everyone is blissfully happy, and rightly so. We are on Mystery Island, one of Vanuatu's gems in the South Pacific Ocean.

Although one would assume such an "island day" to a place like this would quickly become a crowded one, my fellow passengers and I are easily scattered across the minute dot in the ocean.

We each find a spot in the shade, or our own patch of beach or stretch of coral to explore.

Obsessed with underwater life I dip into the cool water and seconds later watch a large school of sergeant majors swim past. They're on an underwater foodie tour, I soon discover, stopping at bommies to feast degustation-style.

I follow them, fascinated by the way they swim in unison; yellow-and-black striped fish waving in the soft current.

Although the hard corals are mainly in tones of grey, musk and mustard, the colours of the sea life are a riot.

I leave the sergeants alone, distracted by the mesmerising blues and purples of parrot fish, and the neon pinks and greens of the smaller moon wrasse.

Nearby are orange and red Christmas tree worms, spiralling out of coral. On the ocean floor, there are mottled brown sea slugs the size of my forearm.

Although I don't venture too far from shore, I am surprised by two things. Firstly, the number of fish this close to the beach and secondly, the complete lack of crown-of-thorns starfish.

The dangerous pests responsible for wiping out swathes of reef around the world, including the Great Barrier Reef, cannot be seen.

Fearing they may be further out to sea I do some research upon my return to Pacific Jewel later in the day. I discover that Mystery Island is in a Marine Protected Area, according to OceansWatch.org, and there is a complete ban on fishing.

I also learn that over the past 20 years Vanuatu has experienced a series of crown-of-thorns outbreaks - "completely eating and killing some of Vanuatu's most pristine coral reefs'', reads an online Radio Vanuatu article (2010).

I can't find any information on the nasty predators being found among the reef around Mystery Island, which I take as a positive sign.

After drying off from my snorkel I meet Barry Nagia, a local of Aneityum Island across the way. He is one of four traditional land owners of Mystery Island, which he explains was once two islands before they joined in the 1930s. He doesn't go into detail about their formation but says one island was solely for hunting and the other fishing.

Barry and his fellow locals still refer to the islands by their two names - Inyeug (the hunting island) and Navinacas (the fishermen's base) - as opposed to Mystery Island, which is the much easier name for tourists.

The island is uninhabited but many locals spend their days here behind wooden stalls selling sarongs and hula skirts to cruise ship passengers. Some also trade in freshly-caught lobsters (a tempting lunch), while others have set up shop near the floating wharf hiring out snorkelling gear and taking tourists on fishing tours.

"Guaranteed to catch a fish,'' reads one painted wooden sign nailed to a stall.

If you're in a silly mood you can also have your photo taken in the Mystery Island Cannibal Soup pot, alongside two rather good looking "cannibals" wielding wooden spears and makeshift machetes. (Cannibalism was the norm many moons ago in this part of the world.)

The morning easily runs into the afternoon and soon it is time to board the tender going back to Pacific Jewel.

As I make my way to the wharf I again run into Barry. He shakes my hand and wishes me a safe journey, before flashing a smile that reveals a missing centre tooth.

It is a smile that is genuine and radiant, and one that is also all-knowing of just how fortunate he is to spend his days with a lady of Mystery.

IF YOU GO

GETTING THERE:

Mystery Island is one of the most southern of the Vanuatu group and is visited by P&O Cruises' Pacific Jewel.

Pacific Jewel is based in Sydney year-round offering a range of cruises to the Pacific Islands, including New Caledonia, Vanuatu and Fiji.

STAYING THERE:

Fares on Pacific Jewel's 10-night cruise to the Pacific Islands departing Sydney on March 18 start from NZ$1128 per person quad share (subject to availability). The superliner stops at Noumea, Lifou and Isle of Pines in New Caledonia, and Vila and Mystery Island in Vanuatu.

Fares include accommodation, main meals, onboard entertainment and activities.

PLAYING THERE:

Carrying 1900 passengers, Pacific Jewel features Aqua HealthSpaFitness, an aerial stage for circus and musical performances on deck and five dining options, including Salt Grill by Luke Mangan.

The ship also offers a three-storey atrium, eight bars and lounges, two swimming pools, whirlpool spas and four kids' clubs.